Note 244 — BOOK V THE RISE AND COLLAPSE OF THE ROMAN EMPIRE
Reading edition
Authorities differ here. Mayor says thumbs up (to the breast) meant death and thumbs down meant “Lower that sword.” The popular persuasion is that thumbs down meant death. Seyffert’s Dict. Class. Antiq. gives this view. See the Encyclopædia Britannica, article “Gladiators.”